1. Field of the Invention
The present invention relates to a printing apparatus and processing method therefor.
2. Description of the Related Art
In general, a printing apparatus is connected to a host apparatus, and forms an image on an output sheet surface in accordance with print data from the host apparatus. In the host apparatus, application software such as a word processor or spreadsheet runs on basic software called an OS (Operating System). When printing from an application, the application transmits print data to the printing apparatus connected to the host apparatus via software called a device driver by using functions prepared in the OS. The device driver is made up of a set of functions that allow the application or OS to absorb the dependency of the function and capability of each peripheral device. A device driver for a printing apparatus is generally called a printer driver.
Printer drivers are classified into those that render print data in an image data (intermediate data) format for output, and those that generate PDL (Page Description Language) as a command directed to a printing apparatus capable of rendering processing. Some printing apparatus cope with only the image data format, and others cope with both the image data format and PDL format.
When a printing apparatus compatible with both the image data format and PDL format receives PDL data, it temporarily stores the data in the reception buffer in the memory. A command analyzer called DLG (Display List Generator) converts the PDL data stored in the reception buffer into intermediate language data called DL (Display List). The data converted into the DL has a list structure corresponding to a band area for each processing unit. The DL is rendered by hardware or software, generating image data of each band. The image data further undergoes color conversion, binarization processing, and the like, generating print data. To the contrary, when this printing apparatus receives data of the image data format, it temporarily stores the data in the reception buffer in the memory, and performs color conversion, binarization processing, and the like, generating print data.
As described above, a printing apparatus capable of rendering processing has complicated processing contents as compared to a printing apparatus capable of receiving only data of the image data format, and requires high-speed performance. To meet this requirement, there is proposed a technique of improving performance by arranging a plurality of processors and performing parallel processes in the printing apparatus capable of rendering processing.
As the technique regarding the performance improvement, techniques disclosed in Japanese Patent Laid-Open Nos. 2000-198240 (to be referred to as reference 1) and 2008-005300 (to be referred to as reference 2) are known. In the technique disclosed in reference 1, the processing speed is increased by parallel processes. More specifically, the first processor performs processes from reception of print data up to conversion of it into an intermediate code. The second processor executes processing of generating rendering data from the intermediate code, color conversion processing, and binarization processing.
Reference 2 discloses a printing apparatus having the first processor, the first memory connected to it, the second processor, the second memory connected to it, a communication interface, and a DMA controller. Before receiving processing data, the communication interface receives size data of processing data, and stores it in the first memory. The first processor controls the DMA controller in accordance with the size data stored in the first memory, and stores the processing data in the second memory.
As described above, a printing apparatus capable of rendering processing often improves performance by arranging and parallelly operating a plurality of processors. As performance improves, power consumption increases in the printing apparatus which includes a plurality of processors and parallelly operates them, compared to a printing apparatus which performs processing using a single processor.
In the technique of reference 1, the first processor performs processes from reception of print data up to generation of an intermediate code. The second processor executes processes up to generation of binary data from the intermediate code. Thus, the first and second processors always run, consuming large power.
In the technique of reference 2, size data is stored in the memory connected to the first processor, and processing data is stored in the memory connected to the second processor. Processing needs to be done using the two processors, and power consumption also becomes large, similar to reference 1.